Grab



May 26, 1925. "1,538,969

' N. I. D. BURKE GRAB Filed Jan. 5, 1924 2 Sheets-Sheet 1 9. 53 Q 59 t i Z5 25 ES 26 an 24 an at 2 a: a

Mew

Patented May 26, 1925.

UNITED STATES PATENT OFFICE.

NORMAN IVAN DURBRIDGE BURKE, OF AUCKLAND, NEW ZEALAND, ASSIGNOR OF ONE-HALF TO THOMAS PHILIP SOMERVILLE, OF AUCKLAND, NEWZEALAND.

GRAB.

Application filed January 5, 1924. 'Serial No. 684,644.

To all whom it may concern:

Be it known that NORMAN IVAN DURBRIDGE BURKE, subject of the King of Great Britain, residing at 11 Ethel Street, Morningside,

in the city of Auckland, Provincial District of Auckland, Dominion of New Zealand, has invented certain new and useful Improvements in Grabs, of which the following is a specification.

This invention relates to grabs used for lifting and removing loose material such as earth, gravel, coal, et cetera, or for excavating channels, berths and other areas, in harbours, rivers and the like, and has for its object the provision of improvements in that type of grab which works with a single rope or chain wherein the lower pulley block is operated vertically on guides between the upper pulley block and the. framework on which are pivotedthe jaws of the grab.

The improvements aim at the reduction of friction and the better balance of the parts which move on the guides so as to prevent the twisting of parts with a consequent jamming of the grab in action, also providing for an improved trip mechanism for locking and releasing the clutches either when the load is dumped on the ground or when it is desirable to release the load whilst the grab is suspended in any position off the ground.

Other novel features are means for compensating for wear on the jaws of the grab, adjusting means for opening the jaws to regulate the amount of material tobe picked up, 'encasing the lower ends of the female guides to prevent material working into the guide tubes, the insertion of rollers in the guides to reduce friction, fitting guide rollers where the rope enters the grab, in addi tion to means for gu ding the bottom block,

so as to cause it to accuratelyalign with the top block, adjusting means between the bottom block and clutches, and a safety lock for holding the grab closed whilst transporting or sluing same in mid air.

In this type of grab there are provided at each side telescopic members comprising on which slide tubes attached to the frame member on which the jaws are hinged, the

lower pulley block being guided up and down the said telescopic members by fixed guides in the form of sleeves to guide the lower block up and down on the telescopic guides, the tubes of theguides being open attheir lower ends.

lVe-aknesses in this type of construction are that the guides wear and allow the telescopic members to twist and cant, causing the jaws of the grab to jam tight in closing or opening, or, alternatively, causing the bottom block to jam tight on the guides in travelling up or down same.

The jamming or seizing ofthe working parts, however, is sometimes caused by sand,

shingleor other material entering the tubes at the lower end and wedging tight on the bearing surfaces inside same. 1

The improvements in the trip mechanismin my invention consists in means for tripping the grab so as to release'theload in mid air, and fixing a locking mechanism thereto so that the load cannotbe accidentally discharged whilst swinging the grab in mid air. i

The means for compensating for wear on the jaws of the grab consist in using movable packing plates b-olted to 'the'lower edge of the top block. The adjusting means for regulating the amount of opening of the jaws and consequently the amount of Inaterial picked up consists in the fixing of toggle levers at each side of the grab, the'lower end of the toggle levers having holes therein, spaced at suitable intervals or equidistant, for adjusting means on to pins secured to the bucket sides, the top end being secured to the spreader arms arranged at each block to guide and align same positively rods secured to the upper pulley block and into position against the lower edge of the upper block. v

The improvements will be further described with reference "to the accompanying drawings wherein Figure 1 is aside elevation of a grab with the buckets in the closed position;

Figure 2 is a similar view to Figure 1 but showing the grab open.

Figure 3 -is a sectional plan of the bottom block.

Figure l is a part sectional elevation enlarged showing the mechanismfor locking the lower pulley block to the frame meniber and to which both jaws are hinged.

Figure 5 is a side elevation of the top and bottom block with the trip mechanism and striking pin in position ready for discharging the load by dumping on the ground or in mid air. s

Figure 6 is a detail of the head of the grab showing the roller guides with the rope passing through same. v

Figure 7 is a detail in sectional elevation of the lower end of the telescopic members.

Referring to the drawing, 1 represents the upper block, 2 the lower block, 3 and l jaws, the latter being hinged at 5 7 both to the frame member 6 and the lower P9 7 lower portion 8 I the length of end of the spreader arms 11 on pins 5 The lower block 2 works on the telescopic guides, one'at each side of the grab, said guides comprising upper rod portions secured at their upper ends by the top cross bars or plates and lower portions 8 shaped to work on said rods and secured at their lower'ends to the frame members 6. The telescopic guides. can be of any desired shape in cross section and when square or circular the roll rs 9 are fitted into the lower end of the rod 7 so as to minimize friction and prevent jamming when the rod 7 is sliding on the lower portion, or when the lower portion 8 is sliding on the upper portion 7. I 1

The rollers 9 are fitted at right angles as shown in Figure 7, two or more pairs of rollers being fitted as required throughout the rod similar to those shown at the lower end of the rod in Figure 7.

The bottom block is guided in its movement up or down the telescopic guides by rollers 9 having their periphery shaped as shown in F i e 3 encircling the guides, the rollers bein an easy working tit on the of the telescopic members, an additional amount of clearance being afforded when the lower block is in its high position as shown in Figure 1 between the rollers and the rods 7, the rollers 9 being fittedin pairs as shown in Figures 3 and 4:. The lower ends (of the guides 8 are closed as shown at' 8" in Figure 7 so as to prevent the entrance of gravel, sand and like material intoIthe guides, the closing being preferably effected by av screwed plug as shown to facilitate cleaning or oiling.

The jaws 3 and 4 are geared together as in existing types by toothed sectors or other v suitable means as at 10' so as'to open and close together, the bucket sections being pivoted at their lnnerends 0 the pins 5 and at their outer ends by the hinge pins 5 fixed at the lower ends of the spreader arms 11.011 which latter the buckets fulcrum or U swing during opening and closing of the same the extent of the opening of the jaws 3 and a can be increased or decreased as required and the quantityof material lifted and discharged varied according to requirements.

Provision is made to overcome undue wear on the edges of the lips 3 and i of thejaws by securing to the lower edge of the top block 1 a number of strips of metal plate '17 the grab when first used being adjusted so that when the lower block 2 is up against the strips 17, thejaws 3 and 4 will be closed with the lips 3 and 4 contactingwith each other, Figure 1'. 1 V r i As the lips 23 and it become worn, the strips '17 are removed one by one or as required to allow the block to move further up the telescopic guides and consequently to close up the wear which has taken place.

on the lips 3, and P and cause same to meet. The lifting rope 18, by means of which the grab is operated, runs through rollers 19, 'these'beingconcaved on the periphery to encircle the rope and prevent same wearing unduly through chafing on the metal. The rope' is reeved through various pulleys in the top and bottom blocks according to the amount of purchase required for closing the jaws of the grab. i

The lower block 2 may be locked to the frame member 6 by any of the well known methodsin use, one form of which is shown in Figured and consists of a pair of clutch members 21 pivoted at 21 Figure km the frame member 6 and connected at their inner ends by a pin 22 passing through slots 23 as shown. Clutches constructed after the manner shown by 21 are vusually weighted at their outer ends 24. so that their strikes the clutches by means of .the projection 27. v The striker plate 27 is adjustable for height by means of lock nuts and bolts as shown in Figure 4:. lhe invention, how-v ever, does not appertain to the system of clutching, the improvement consisting in the mechanism for locking and releasing the clutches so as to trip the load either on mechanism for locking and unlocking the clutches is to prevent the trigger 27 from jamming tight due to the plate 38 sticking on the pin 39 owing to friction and also to the spring 28 not operating in a direct line with the guide rod 29. a

To prevent this, the spring 28 which keeps the trigger 27 in the locked position Figures 4 and 5, is made to encircle the guide rod 29. The outer end of the tri ger 27 is shaped at 30 to take, if necessary, an adjustable balance weight, the upper end 31 being turned at right angles for engaging with the striking pin above.

The striking pin 32 projects above the top block as shown Figures 1. 2 and 5, the rod forming" the striking pin working in guides 33 and normally held up to the position shown in Figure 5 by the spring 34. the lower end of which bears upon' the upper surface of the guide 33 and the upper end against a collar 35 which latter is pinned or otherwise secured to the striking rod 32, the lower end of the striking pin having a projection 36 as shown in Figure 5. When the head of the striking pin 32 contacts with the plate 37 the part 31 is depressed lifting the trigger 27 clear of the clutches 21 s as to dump the load in mid air.

Previous to the projection 36 making contact with 31 the lower end of the rod 32 depresses the arm 48, causingthe foot of 44 to swing to the right clear of the locking rod 4.3.

It is important both in the case of the guide rod 29 and the striking pin32 that the spring operates directly in the line of action of the rod. The lower end of the guide rod 29 has a projecting plate 38 which lYiO'lQCFR sulliciently to strike the pin 39 fixed to the trigger 27. Over the pin we fit a roller 39 to revolve easily on the pin and prevent the plate 38 sticking on same by friction.

To ensure the bottom block aligning true with the top block when in the position shown in Figure 1, we fix two projecting guide plates 40 to the inside of the bottom block as shown in Figure 4, the plates being turned inwards and upwards as shown so as to enter readily between the plates of the top block when the lower and upper surfaces of the top and bottom blocks come to gether. The packing strips 17 which are secured to the lower edge of the top block 1 5 a spiral springis shown, one end bein anchored to the pivot pin 46 and the other are bolted as shown in Figure 5 tothe flange by an angle iron member 41'as shown.

In use, the grab withthe jaws 3 and4 open'andlower block in the position shown by Figure 1 is lowered on to thematerial from which the load is to be removed. The

rope 18 is slackened suflicient to allow the lower block 2 to slide down the telescopic guides 7 and 8 by means of friction rollers 9. VVhe'nthe adjustable projection 27 on the lower block strikes the slotted inner ends of the clutch members 21, the hooks 25 are caused to engage over the projections 26, after which the tension on the spring 28, through the medium of plate 38 striking the roller pin 39 depresses the inner end ofthe trigger 27 as shown in Figures 4-.and

t acts with the upper block, the jaws 3 and r 4 are fully closed and the grab is swung to the position required to dump the load.

WVhilst transferring the load, the trigger 27 is prevented from releasing the clutches by the locking rod 43 bearing againstthe safety catch 44 which is normallyheld' in the locked position Figure 5 by spring 45 which may be of any 'design suitable forholding the safety catch locked. In Figure hearing against the vertical member of 44.

In its normal locked position the lower end of the safety catch 44 bears against a stop 47 fixed to the top frame or plate members.

In swinging or transporting the load in mid air the lower end of the rod 43 prevents the trigger 27* lifting high enough to clear the hooks 25 on the clutches 21, thus keeping sa nelocked should the grab strike an obstruction of any kind.

If it is required to dump the load in mid air, the grab is hoisted to the position shown in Figure. 1 so that the head of the striking pin 32 contacts with the plate 37 which op eration first depresses the arm 48 on the safety catch 44, causing same to swing clear of the locking rod 43, after which it depresses the outer end of the trigger 27", lifting the inner end of same clear of the hooks V 25 on the clutches 21.

IV hen. the load is to be dumped on the ground, immediately the grab is lowered onto the material, the bottom block is run down a few inches, enough to allow the rod 43 to be pushed up and to let 27 strike the inner ends of 21, which allows the outer end of the trigger 27 assisted by the balance weight 30, to fall by gravity, in turn allowing. the clutches to release the hooks 25' from projections 26, the outer weighted ends 24: falling by gravity.

The travel on rod 43 is only about onehalf inch or suflicient to prevent the trigger 27 from disengaging when the lower'blockhas travelledabout half an inch, the locking rod 43 is pushed by itsspring 19 to its highest position with the collar 50 resting against the guide 38. The bottom block2 is then further lowered until the projection 27 strikes the inner slotted ends of clutches 21, which immediately takes the weight off the trigger 27, allowing same to fall down at its outer-end, carryingweight 30, and rise up at its inner end 27 After clutches 21 are disengaged, an upward'pull on the rope 18 discharges the load.

If it should be required to open the grab by pulling on a rope 42 fixed to the top end of trigger 27 instead of using the overhead plate 37, the safety lock 44 would have to be removed.

To prevent undue strain being placed upon the rope 18 when the striking pin 32 strikes the plate 37 the latter can be made slidable on the frame carrying the rope block instead of being rigidly fixed to same.

I claim 1-,

1. In a grab of the type operated by a single rope or chain on the block and tackle principle, an upper sheave block, a lower sheave block, a frame below the latter, a pair of gravity catches pivoted on the frame and adapted to engage the lower block for securing the frame and block together, a latch, engageable with one of said catches for temporarily securing the same against movement, a roller arranged on the latch, a sliding rod mounted on the lower block and having an arm engageable with said roller forten'iporarily preventingthe movement of the latch, a spring surroundingsaid rod for normally holding said arm inposition to prevent the actuation of the latter, and an actuating'member for the latch arranged on the upperblock."

2. In agrab as claimed in claim 1, a projcction on the latch, and an adjustable weight arranged on the projection adapted to assist in swinging the latch out of engagement with the catch with which it cooperates.

3. A grab as claimed in claim 1 in which said actuating member includes a slidable pin, a spring surrounding the pin for normally holding the same in its upper position, and a foot element at the lower end of the pin arranged to strike the latch when' the pin is depressed.

4. In a grab as claimed in claim 1, a spring pressed pin carried by the lower block and cooperating with the latch to prevent the latter" from disengaging the catch with which it cooperates, and an auxiliary latch for said pin operated by said actuating memlower sheave block movable relatively to the upper block and adapted to contact with the latter, adjusting means between said blocks for limiting the extent, of movement of the blocks toward each other, a frame beneathv the lower block, latchingmeans for connecting the frame and the lower'block, jaws pivotally connected to the frame, arms pivotally connecting said jaws to the upper block, and means for causing said jaws to open and close in unison.

7. A grab including an upper sheave block, a lower sheave block, extensible means connecting said blocks, a frame below the lower block, means for latching the frame to the lower block, jaws pivotally connected to the frame, arms pivotally connecting the jaws to the upper block, toggle links connecting the intermediate portion of said arms to said jaws, and means for varying the effective length of the links.

8. In a grab of the type described, upper and lower sheave blocks, and means for ensuring the lower block aligning with the upper block, said means consisting of guide plates secured to the inner sides of one of said blocks, projecting beyond one end of that block and having its, free ends tilted toward each other, so as to engage the other block when one block is moved toward the other block.

NOR-MAN IVAN DURBRIDGE BURKE. 

